This is one of a series of “Notes” I published on Facebook. Since Facebook has discontinued the Notes feature, I am publishing that series here on my blog.
Back in September I was asked by an officer of the local amateur radio club to say a few words about our (hopefully) upcoming new bands: 630 meters (472-479 kHz) and 2200 meters (135.7-137.8 kHz). I didn’t have much to say. I hadn’t thought much about these bands. It might have ended there but for my interest in early radio equipment. Several weeks later in one of the antique transmitter building forums I saw a post about “630 Meter Crossband Night” which is an event held each November. During this event, several Canadian amateurs call CQ on 630 meters and listen for U.S. hams to call them on 160, 80 or 40 meters. These bands are already allocated to amateurs in Canada and many other countries. In the U.S. there are a number of stations operating with FCC Part 5 Experimental licenses. There is more than the usual CW activity among these stations on Crossband Night compared to other times. I figured I might as well give it a go and see if I could hear anything at all. As is often the case with me, A plus B equals hang on, we’re about to take a U-turn and go off on another wild adventure!
My station transceiver, a Yaesu FT-2000, has a general coverage receiver which tunes down to 30 kHz so I figured I would be all set there. I didn’t know if any of my existing antennas would work at this frequency. I have several Beverage antennas ranging in length from just over 500 feet to just under 700 feet. They work well on 160 meters but at 630 meters they are on the order of a quarter wavelength long. That is too short to work as a Beverage. At best I figured they might perform as random short pieces of wire oddly coupled to coax and the ground!
It didn’t take long to find my first signal on 630 meters: VO1NA in Newfoundland, Canada. Joe’s CW signal was excellent, several S units above the noise. I called on his 80 meter listening frequency and had a crossband QSO with him. Later I had a similar QSO with VE3OT in Ontario, a distance of over 600 miles. Clearly I could in fact hear something on this mysterious medium frequency band! I heard a number o the FCC Part 5 stations as well, including WG2XIQ in Texas. Unfortunately they are not allowed to communicate with stations operating in the Amateur Radio Service so crossband or any other form of two-way contact is not possible.
As for antennas, I discovered that I could hear several stations on my 80 meter inverted V and even one or two on my 20-10 meter beam. The Beverages were a clear winner though. Oddly I would discover that night and more so in the nights which followed that my west-facing Beverage had the lowest noise level of the eight directions available and was the best receive antenna for 630 meter signals from all directions. As for just what causes this, I don’t know. They are after all acting as short random length wires oddly coupled to coax and ground. There is no telling what the pattern is or how they might be interacting with each other or with other structures.
As a frequent user of the ON4KST internet chat site for low bands (160-40 meters), 6 meters and VHF/UHF (2 meters and up), I was aware Alain also had a chat page for the low and medium frequency bands. Naturally I checked in there to see who was doing what and get a better feel for activity. It didn’t take long to start assimilating the nature of the beast. It seems that in Europe, where amateurs in many countries have access to 630 meters, two-way QSOs are taking place on CW and various weak signal digital modes. There is also a lot of beaconing using WSPR (Weak Signal Propagation Reporter) taking place. In North America, since there are so few who can legally communicate with each other due to licensing issues in the U.S., the vast majority of activity is on WSPR. There is some CW and JT9 (another weak signal digital mode), and from time to time QRSS (extremely slow CW meant to be read visually from a “waterfall” on a computer screen). I began checking into the chat site every evening and it was immediately obvious my exploration of these bands would not end with Crossband Night. Hang on. Here we go again!
I have never been much for digital modes. It is no secret I find the inherent reduction in what constitutes a complete QSO these modes have brought very disturbing. WSPR, however, is quite interesting. As the name implies, it is a beaconing mode intended primarily for propagation study and monitoring. Without getting into it too deeply, there is a 200 Hz “window” on each band (2200 meters up through microwaves) where this mode is used. WSPR transmissions are two minutes long each, precisely timed. The information encoded in each transmission is call sign, grid square and power (in dBm) of the transmitting station. One can adjust how often the transmissions are made, from 100% (continuous transmission using every two minute time slice) down to 1%. For example, 25% would mean the software transmits one out of every four two-minute time slices or about once every eight minutes. Usually the slices chosen for transmission are randomized to help alleviate interference among stations or any one station not ever hearing another because they are both transmitting at the same time. On the receiving end, the software monitors the entire 200 Hz segment and decodes any WSPR transmissions it hears. Since WSPR is a very narrow bandwidth mode, many signals can fit into the small slice of spectrum without overlapping. One interesting feature of WSPR is the ability to upload data from all decoded transmissions to the WSPRnet.org web site. WSPRnet provides mapping of activity, showing propagation paths in real time. It also provides access to the database of received decodes, allowing users to extract a variety of information about who is hearing who and how well. The mode can pull signals from deeper in the noise than the human ear, making it possible to receive signals more traditional modes could not. WSPR is worthy of an article in and of itself, so I won’t go into it too deeply here.
Example of a WSPRnet.org map, showing stations being received by N1BUG on the 630 meter band
It wasn’t long before I heard my first signal from Europe on 630 meters. Wow! It would be followed by several others on the better nights. Hawaii also showed up in my decode list on several occasions. This is amazing, considering that most of these stations are running one watt effective radiated power (ERP). They may be running many times that out of the transmitter, but the average antenna on 630 meters is very small compared to a wavelength and quite inefficient, meaning that only a small part of the power fed to it is actually radiated. The rest goes to various losses in loading coils, ground system, etc. Consider that a quarter wave vertical would be 495 feet tall and you can see that physically short antennas are going to be necessary for most of us! I mentioned before that WSPR can pull signals from much deeper in the noise than the human ear. But, at times some of the stronger European stations have been clearly detectable to my ear. I could have copied them on CW.
630 Meters is fun, but I have always been a creature of extremes. The real challenge here was obviously going to be 2200 meters. I wanted to hear a signal on that band! After several nights listening without success I knew I had work to do. Not only were there no signals, but I could not even hear a change in noise when I disconnected the antenna. Either the antennas weren’t working or my receiver wasn’t working at this frequency. Perhaps both. One night while listening on Old Reliable (my 80 meter inverted V), I managed to decode WD2XES in Massachusetts on WSPR and VO1NA on QRSS60. Signals at last! Although neither was detectable to my ear, I at least could claim that I had intercepted and decoded signals on this band. Of course that only made me want more, so I redoubled my efforts.
During the course of investigation I found my FT-2000 is extremely deaf on 2200 meters. It needed a lot of help! I set about building a preamp to bring signals up to a level the receiver could detect. 22 dB gain wasn’t enough, but it did bring up signals in the AM broadcast band enough to cause signal mixing IMD products in my receiver. Suddenly the whole spectrum was a mess of howling, squealing, squawking and wailing from these unwanted mixes. I was going to need a filter to kill the strong signals up in the medium wave broadcast band. So I set about to build one. I have already written an article on that adventure. It was a great learning experience. Then I built a second preamp. Now with 44 dB gain ahead of my receiver I began to routinely hear signals. WD2XES was usually audible; WH2XND in Arizona was easy to decode on WSPR and sometimes just barely discernible to the ear. Even with all this, the FT-2000 still was not good enough at this frequency. I still couldn’t hear any drop in noise floor when I disconnected the antenna. I am now experimenting with a low frequency converter that takes the 10 kHz to 300 kHz spectrum as input and provides output at 10.01 to 10.3 MHz for the receiver. This finally solves my sensitivity problem, and without the use of preamps. It does introduce a frequency drift problem which I am trying to resolve. With the converter, WH2XND is being decoded over 100 times in the average night and is often clearly audible. Progress! As for antennas, on this band I find the southwest Beverage works better than any other. It isn’t quite the same as on 630 meters. Down here this is not the quietest Beverage but it seems to pick up signals better than any other regardless of direction. These wires are less than one tenth of a wavelength long at this frequency. It is a wonder I hear anything.
I mentioned QRSS a couple of times. I find this mode very intriguing. It may well be the ultimate mode for extracting signals from deep in the noise floor. Using a variety of submodes of differing speeds, QRSS can integrate a signal over time, detecting it at weaker levels than anything else I am aware of. Submode QRSS60, for example uses dots of 60 seconds in duration. Dashes are 180 seconds. This is an extremely slow mode. It would take 33 minutes to send my call sign ‘N1BUG’. But it can dig very deep for signals. I would be quite interested in attempting transatlantic QSOs using this mode on 2200 meters, assuming we get access to the band as amateur radio operators.
VO1NA received on 2200 meters using QRSS60 mode. Although the first dash of the letter O is a bit broken up due to a signal fade, you can essentially read his call sign from the screen. This is how QRSS is received.
There is a good amount of activity on 630 meters. It will be very interesting to follow propagation trends as we head into solar minimum. Some say this could be the deepest solar minimum since the invention of radio. Unfortunately I cannot say the same for 2200 meters. Perhaps it is just too immense of a challenge for most, or perhaps what can be done there hasn’t received as much publicity as the higher band. The only stations transmitting regularly on 2200 meters in North America are WH2XND is Arizona and WE2XPQ in Alaska. The latter is practically an impossible path from here in Maine given the high latitude (auroral oval to contend with) and the fact that his antenna is directional and does not favor us. WD2XES in Massachusetts is on some evenings. I have only seen VO1NA once. I wish there was more activity on this band. Actually I wish I was capable of transmitting on the band, but that is another story.
I am continuing to learn about these bands and exploring technology that is new to me. I am learning a lot of things I didn’t expect along the way. In a subsequent installment, I will talk about basic equipment and antenna options, as well as provide ideas on resources for further study. I have spent several hours every day for over a month studying various ways of getting on these bands (particularly 2200 meters). There is a lot of published work out there and some very interesting kit options for equipment.